These fabulous socks are made of a 60% Merino Wool. They keep your feet warm and comfortable but are fine and slim enough to fit in most shoes. The Nylon blend gives longevity. As they are a health sock, there is not elastic top to constrict around the calf. Small size suits Euro 35-41, Medium 40-45, Large 46-51 60% Fine Merino Wool; 38% Nylon; 2% Elastane. Short warm wash on medium cycle. May be tumble dried on warm only. Do not bleach. Do not professionally dry clean. Do not iron.